Ok I saw this done here I think. Try two safety pins the ones that look like tiny skinny nails, cut of the ends and drill or punch them to the sides of the helmet your using. after you make the holes take them out and set your visor put a little bit of superglue on the pins and stick them in but be careful not to get any glue on the visor. This should work . The only thing is the tightness of the visor might be a little loose try it see what happens.
